[PATCH] Issue916: tag ought to work sanely even when there is no checkout

[Jesse Glick]

Matt Mackall wrote:
> The current behavior is perfectly consistent.

Consistent, but almost certainly unwanted.

1. If null is "checked out", it is generally because you just do not 
want a checkout (say because you are running a server), not because you 
really wanted to start creating a new root. If you really did want a new 
root, you could always

hg up null
touch .hgtags
hg add .hgtags
hg ci -m 'starting a fresh root branch for tags, for some odd reason'

2. Checking out tip just to add a tag can be very slow and wasteful of 
disk space for a large repository.

> I'd rather have the "creates a new head" sort of warning.

Might be better than nothing, but seems to me like "I just did something 
you very likely did not expect or want, so now I am informing you of this".

If the first patch is not acceptable, I would rather go with option #2 
from Issue916, i.e. just abort if there is no (real) checkout, rather 
than quietly doing something silly.